Not as interesting a post, as the topic may suggest!
I have seen many BA 757s and 737s in new and old colours with a ring around the nosecone. They are black rings, so they stand out a lot against the new white scheme. Does anyone know their purpose?
I also saw a couple of their 767s in the old scheme with the chequered black and white circle on the nose. (Like the crash test symbol!!) I assume that it is something to do with the center of gravity along the longitudinal axis of the aircraft, but why?